Hello I'm new here, I have a 2005 chevy duramax lly. The modifications I have done is efi live, egr blocker plate, 4" exhaust nothing too fancy. I live my truck in stock, I have the 5 tune switch. Sense I have owned the truck going on a year now, everytime I try to pass someone or quickly speedup were it hits overdrive, it will not shift at all. It hickups, we're it stops for a few seconds and kicks back on until I let go of the throttle then it will shift into the next gear. I do not get any codes, trans doesn't go into limp at all either. I have no idea besides possibly the sensors?